Troubleshooting guide

In this example you can see that the SID is a non−zero number, and that both the RemMAC and LocMAC
fields are populated. The other field of interest is the Vast, which indicates whether PPP has been successfully
negotiated and authenticated. If the Vast is UP, PPP has been successfully negotiated and authenticated, and
you can proceed to the Why can I access some web pages with PPPoE but not others? section of this
document. If the Vast is DOWN, continue with the next section.
Are you receiving a PPPoE response from the aggregation router?
If you do not have an active PPPoE session established, you need to issue the debug vpdn pppoe−events
command to determine what PPPoE is not coming up.
Router#debug vpdn pppoe−events
*Mar 3 21:49:38.030: Sending PADI: vc=8/35
*Mar 3 21:49:38.030: padi timer expired
*Mar 3 21:50:10.030: Sending PADI: vc=8/35
*Mar 3 21:50:10.030: padi timer expired
*Mar 3 21:50:42.030: Sending PADI: vc=8/35
*Mar 3 21:50:42.030: padi timer expired
*Mar 3 21:51:14.030: Sending PADI: vc=8/35
*Mar 3 21:51:14.030: padi timer expired
*Mar 3 21:51:46.030: Sending PADI: vc=8/35
*Mar 3 21:51:46.030: padi timer expired
Router#undebug all
In this example, the Cisco DSL Router is continuously sending PPPoE Active Discovery Initiation (PADI)
frames to the ISP with no response. The PADI frame is the first in a series of PPPoE call−setup frames. If
your ISP does not respond with a PPPoE Active Discovery Offer (PADO), PPPoE negotiation will not
succeed. The only solution for this problem is to contact your ISP.
If you are successfully negotiating PPPoE, your debug vpdn pppoe−events output will look like the
following:
Router#debug vpdn pppoe−events
*Mar 3 21:49:38.030: Sending PADI: vc=8/35
*Mar 3 21:50:10.030: PPPOE: we've got our pado and the pado timer went off
*Mar 3 21:50:35.030: OUT PADR from PPPoE tunnel
*Mar 3 21:50:50.030: IN PADS from PPPoE tunnel
Router#undebug all
If PPPoE is successfully negotiated, continue with the next section about troubleshooting PPP.
Is PPP negotiating properly?
If Layer 1 is up and you have the correct VPI/VCI, the next step is to make sure PPP is coming up properly.
To accomplish this, you need to run a series of debug commands on the Cisco DSL Router and interpret the
output. The primary debug you will use is debug ppp negotiation. The following output of this command is
an example of a successful PPP negotiation:
Router#debug ppp negotiation
PPP protocol negotiation debugging is on
Router#
2w3d: Vi1 PPP: No remote authentication for call−out
2w3d: Vi1 PPP: Phase is ESTABLISHING
2w3d: Vi1 LCP: O CONFREQ [Open] id 146 len 10
2w3d: Vi1 LCP: MagicNumber 0x8CCF0E1E (0x05068CCF0E1E)
Cisco DSL Router Configuration and Troubleshooting Guide